1. Field of the Invention
This invention relates to woodworking power tool accessories in general and, more precisely, the present invention is an adjustable fence guide designed primarily for use with circular power saws for cutting large flat panels such as plywood.
2. Description of the Prior Art
Fence guides are well known in the field of woodworking for keeping the edge of the wood being sawn parallel with the cutting blade in order to produce a perfectly straight cut. Most typically non-portable woodworking equipment including table saws and some band saws come equipped with adjustable guide fences primarily designed for this purpose. Hand held portable electric saws however are not furnished with inherent means for producing straight cuts since they are generally used for non-critical applications where complete accuracy is not essential such as the framing stage of building construction. Hand held saws, such as electrically powered circular saws and saber or jig saws, are not only useful in that they are portable and can be transported easily, but they can also create cuts which would be difficult or impossible to do on a conventional table saw. One such procedure which is extremely difficult to do with a table saw is rip a section of plywood. Due to the large size of the plywood, generally 4 X 8 foot panels, and the limited width adjustment range of the table saw fence guide, hand held circular saws are often used to free hand cut the plywood following only a penciled line. Although fence guide attachments for power circular hand saws are available, generally, they are adjustable arms affixed to the base of the saw with a lip or guide on the opposite end for engagement with the edge of the plywood. This type of device works only if the edge of the plywood is straight, otherwise, inperfections on the edge are reflected in the cut. Many times a board or plank the length of the plywood is merely clamped onto the surface of the plywood with the edge being used as a guide fence for the circular hand saw. Using this technique, however, additional time consuming measurements must be taken to allow for the width of the circular saw base and blade which extend beyond the edge of the board being used as a guide fence.
A search conducted at the U.S. Patent Office in the classes and subclasses 83/455, 565, 567, 745, 749, and 821 did not reveal a device relatively similar to the operational structure of my guide fence. Most disclosures showed upper and lower clamp plate arrangements or lateral guide rods on which a power saw or a router rides. Although patent number 4,307,513 issued to Genge, Dec. 29, 1981, uses an edge guide, the supporting surface is quite large and cumbersome and the clamping mechanism is somewhat complicated. Other patents examined are included herewith for reference purposes.
Having seen nothing in the prior art or in the marketplace comparable to the simplicity and usefulness of my device, I therefore have concluded that may guide fence is a better concept. As my simple device provides new and useful improvements over existing portable guide fences by helping to reduce set-up time and by providing means to produce a truly straight cut, the invention appears unique to the field.